In modern underground mines for mining coal or other solid materials, the general practice is to carry the mined material from working areas to the surface on belt conveyors, usually with a main or mother conveyor leading along a main shaft to the surface and satellite or feeder conveyors leading from working areas and discharging directly or, through one or more intervening conveyors, indirectly onto the main conveyor, depending on their proximity thereto.
Electric lines and equipment for supplying and using electric power in underground coal mines, are subject to approval and periodic inspection under regulations of the Bureau of Mines designed particularly to safeguard against hazards, such as fire and explosion, attendant the exposure of such lines and equipment to coal dust, and are correspondingly expensive both in initial cost and maintenance. Despite the expense and potential hazards, it nonetheless is the practice in modern coal mines to make electric power available underground and drive by electric motors not only the drive pulleys of the belt conveyors but also auxiliary equipment required in the mine, such as pumps for draining water from puddles or pools accumulated in depressions in shaft floors, rock dusters for mixing pulverized limestone dust with the air to control coal dust generated in the working areas and along the conveyors, and tools of various types.
Recognizing shortcomings of using electric power in underground mines, Roark, in U.S. Pat. No. 4,041,785, issued Aug. 16, 1977, proposes to operate auxiliary equipment, such as pumps, mechanically by taking power off the return flight of one of the belt conveyors in the mine. In Roark's arrangement, a pair of drive rollers, drivably connected and normally spaced below the return flight of the conveyor belt, are forced into driving engagement with the return flight by a pressure roller positioned between the drive rollers on the opposite side of the belt and swingably mounted and manually positionable for disengaging the return flight from or varying its pressure on the pair of drive or, as termed by Roark, "drivable" rollers. Resembling Roark in replacing electric power by power taken off a belt conveyor, the present invention is particularly directed to an improved system for powering auxiliary equipment by a conveyor belt in which power is taken off the belt's advance flight.